Evaluation of composts as biofilter packing material for treatment of gaseous p-xylene

Composts are often employed as a packing material of a biofilter for treating gaseous streams contaminated with volatile organic compounds or malodorous chemicals. In order to select a good packing material for a biofilter, two commercially available composts in Korea, pig manure compost (PMC) and food waste compost (FWC), were studied during the treatment of gaseous p-xylene. The composts were used as purchased or after washed with water to remove water-soluble nutrients and microorganisms on the compost surface. Washed composts exhibited a shorter start-up period for a biofilter to reach a high and steady degradation level of p-xylene. Nitrogen limitation was experienced when a biofilter was operated without adding a supplemental nitrogen source. The soluble nitrogen content was initially higher in PMC than in FWC, but the latter had a higher content of insoluble nitrogen and a lower activity of the nitrification which converts NH₃-N to NO₃-N. The biofilter packed with FWC yielded a lower loss of nitrogen as leachate and exhibited a more stable performance for a longer period of 150 days with the maximal elimination capacity of 21 g p-xylene m^-3 h^-1.